In this paper, a genetic algorithm (GA) is used to synthesize and optimize the excitation weights of a planar array for satellite communications based on ITU Radio Regulations 2016. The planar array is arranged into symmetric square lattices of subarrays. Each subarray is assumed to be consisting of 4×4 isotropic, uniform- spaced, and uniform-weighted elements. The proposed arrays are assumed to be consisting of 4×4 and 16×16 subarrays. A genetic algorithm is used to optimize the weights at the subarrays. Three different cases are studied in the paper. The first case is dealing with an amplitude-only weighting synthesis of the planar array. In this case the ratios of amplitude weights of subarrays are varied continuously from 0 to 1. In the second case, a phase-only synthesis of the planar array is discussed where the phases are varied in a continuous range between -π/2 and 0° while the amplitudes of all subarrays are the same. In the third case a complex weight synthesis is presented. In this case the ratios of the amplitudes are constrained between 0.7 and 1 whereas the phases are varied continuously from -π/2 to 0°. Moreover, the amplitude is varied with both continuous and discrete values. A comparison between the three methods is presented to develop the optimum technique for feeding an antenna array for satellite communication systems.